1. Field of the Invention
The present invention relates generally to the field of respiratory masks.
2. Description of the Background Art
A respiratory mask is a device used to deliver a gas or gases to a person. The mask shell is fitted over a face of the person in order to supply a gas to a respiratory system of the person. A related art respiratory mask generally includes a mask shell, a gas supply hose, and a vent aperture. The related art vent aperture is typically a simple hole in the mask shell that allows gas to escape the related art mask shell. Exhaled air is flushed out of the related art respiratory mask by the positive pressure generated by the gas supply hose. This is taught by Rapaport U.S. Pat. No. Re. 35,339.
The related art respiratory mask may be used to deliver any variety of gases, including air or oxygen, and a variety of medicines or treatments. A strap or other attaching means (not shown) may be affixed to the related art mask shell and may be fitted over the head of the person. Constant pressure gas is therefore delivered, with the related art vent aperture maintaining a substantially constant pressure in the mask. This is referred to as a continuous positive airway pressure (CPAP) mask. The related art vent aperture allows the patient to exhale without accumulating excessive carbon dioxide in the mask.
Several drawbacks exist with the venting aperture of the related art respiratory mask. First, the air circulation within the mask shell and vent aperture may create annoying noises. The related art aperture may create a noisy, turbulent airflow. Second, a jet of air from the vent aperture may impinge on the wearer or on nearby persons. The vent aperture and a resulting air jet are relatively close to the face of the wearer, and will in all likelihood be in the region of persons near to or conversing with the wearer. As a result, these drawbacks may affect compliance with a gas therapy.
Therefore, there remains a need in the art for an improved respiratory mask.
In accordance with the present invention, a low noise exhalation port for a respiratory mask comprises a venting device having a body including a proximal end operably connected to an internal area of said mask to vent carbon dioxide exhaled by a person from said mask, and a distal end, said venting device venting a gas out of said respiratory mask so as to substantially reduce inhalation by said person of the exhaled carbon dioxide. An exit passage portion is provided at said distal end and extending partially through said body and communicates with an exterior of said mask, said exit passage portion having a substantially regular cross-sectional area. An entrance passage portion is provided at said proximal end and extends partially through said body, said entrance passage portion communicating with an interior of said mask and further communicating with said exit passage portion, said entrance passage portion decreasing in cross-sectional area from said interior of said mask to said exit passage portion.